Apparatus for pumping tools into and out of a well

ABSTRACT

A system and method for pumping tools into and out of a well through fluid circulation passages in the well including fluid input and return passages communicating with each other in the well bore and with surface apparatus for controlling fluid flow through said passages. The surface apparatus includes a manifold system for directing flow through the well circulation passages in either direction and includes variable choke means in the fluid return portion of the manifold for a controlled back pressure on the well passages and pressure and flow rate measuring means for monitoring fluid flow in the well passages.

United States Patent [72] Inventors PhillipS. Sizer Dallas; Harry E. Schwegman, Richardson, both of Tex. [21] AppLNo. 682,874 [22] Filed Nov. 14, 1,967 [45] Patented Sept. 28,1971 [73] Assignee Otis Engineering Corporation Dallas, Tex.

[54] APPARATUS FOR PUMPING TOOLS INTO AND Primary Examiner-Ian A. Calvert Attorney-E. Hastings Ackley ABSTRACT: A system and method for pumping tools into and out of a well through fluid circulation passages in the well including fluid input and return passages communicating with each other in the well bore and with surface apparatus for controlling fluid flow through said passages. The surface apparatus includes a manifold system for directing flow through the well circulation passages in either direction and includes variable choke means in the fluid return portion of the manifold for a controlled back pressure on the well passages and pressure and flow rate measuring means for monitoring fluid flow in the well passages.

PATENTEDSH'ZBBII 'sum 1 or 3 mvsmons Phillip 8.5m" Harry E. Schweqmun 7 M e? yap EATTORNEYS Pmmmsmam 3.6085631 sum 2 or 3 INVIZNTURS' Phllllp S. Sizer Harry E. Schweqman APPARATUS IFGR PUMPING 'lllLS INTO AND OUT OF A WELL This invention relates to well tools and more particularly relates to a well system and method for pumping tools into and out of a well through fluid circulation passages within the well.

It is a particularly important object of the invention to provide a new and improved system for pumping well tools into and out of a well.

It is an additional object of the invention to provide a well system including supply and return fluid flow passages in a well connected with a surface manifold for supplying fluid under controlled conditions to the well flow passages for flow in either direction in the well through the passages.

It is another object of the invention to provide a surface manifold for a well flow system for supplying and receiving or returning fluid in either direction through flow passages of the well system.

It is a further object of the invention to provide a surface manifold system for fluid supply to and return from a well flow system including manual and automatic choke means for imposing a controlled back pressure on the well system.

It is a still further object of the invention to provide a compact portable surface manifold system which is readily movable from one well to another for controlling fluid flow between a storage tank and a well flow circulation system.

It is another object of the invention to provide an automatic choke for use in controlling fluid flow responsive to fluid pressure communicated to the choke.

It is still another object of the invention to provide a system for supplying fluid to and returning from a well in a closed circuit well flow circulation passage system including means for determining the pressure and flow rate of fluid flowing through the manifold system into and returning from the well system.

Additional objects and advantages of the invention will be readily apparent from the reading of the following description of a device constructed in accordance with the invention and reference to the accompanying drawings thereof, wherein:

FIG. 1 is a schematic view of a well system embodying the invention showing a fluid circulation control manifold with its valves positioned for pumping fluids into a well in one tubing string and returning the fluid in another communicating tubing string;

FIG. 1A is a fragmentary schematic view of an alternate form of fluid circulation control manifold with its valves positioned to direct fluids along the same flow pattern or the manifold shown in FIG. 1;

FIG. 2 is a fragmentary schematic view similar to FIG. 1 illustrating the valves of the manifold of the system positioned for fluid flow in the tubing strings in a direction opposite to that of FIG. 1;

FIG. 2A is a fragmentary schematic view of the manifold of FIG. 1A with the valves adjusted to direct fluids in a direction opposite to that of FIG. 1A;

FIG. 3 is a side view in elevation of a portable surface manifold unit embodying the invention and schematically showing metering and recording units connected therewith for determining pressures and flow rates within the system;

FIG. 4 is a top view in elevation of the manifold unit of FIG.

FIG. 5 is a left end view of the manifold unit of FIGS. 3 and 4;

FIG. 6 is a longitudinal top view, partly in section and partly in elevation, of the automatic choke used in the manifold unit; and,

FIG. 7 is a further enlarged view in section of the choke of FIG. 6 taken on the line 7-7 of FIG. 6.

Referring to the drawings, a well system embodying the invention includes a manifold 21 shown in a specific compact form in FIGS. 3-5, connected between a storage tank 22 and a well 23 equipped with tubing strings 24 and 25 interconnected within the well below a packer 26. The tubing strings communicate near their lower ends through a crossover connection 27 which permits fluid communication in either direction between the tubing strings. The tubing string 24 includes a suitable landing nipple 28 at its lower end below the crossover connection in which a bottom plug, not shown, is releasably locked for closing the lower end of the tubing string. Similarly, the tubing string 25 has a landing nipple 29 which releasably supports safety and check valve apparatus, not shown, below the crossover connection so that fluids entering the well through the casing perforations 23a may flow into the lower end of the tubing 25. The check valve prevents flow from the tubing string into the well, while the safety valve closes the tubing string responsive to excessive well pressure and other predetermined well conditions.

The tubing strings 24 and 25, with the crossover 27, provide a U-tube flow passage pattern in the well allowing fluid circulation from the surface and return for pumping well tools into and out of the well in the tubing strings. For example, well tools such as the bottom plug and the safety and check valve apparatus in the landing nipples of the tubing strings may be installed or removed by such pumping procedures. These procedures are especially useful in underwater or other relatively inaccessible oil wells where installation and removal of tools are accomplished from remote control stations. Equipment used in such procedures is illustrated and described at Pages 3779-3781 of the Composite Catalog of Oil Field Equipment and Services, 1966-67 Edition, published by World Oil, Houston, Texas.

The fluid storage tank 22 is connected by a conduit line 30 having a pump 31 connected therein into an input line 30a of the manifold 21. A return or discharge line 32 of the manifold is connected into a separator 32a having a discharge line 320 leading back to the storage tank. A flowmeter readout panel 33 and a recorder 34 are connected with the manifold for indicating input and return flow rates and recording pressure conditions and total input in the system. The readout panel and recorder are connected together by a conductor 34a. Fluid is supplied from the tank through the manifold into one of the tubing strings of the well and returned through the other tubing string and manifold to the tank. The fluid is pumped into the well through either of the tubing strings while being returned from the well through the other tubing string for various well-servicing purposes including pumping well tools into and out of the well in the tubing strings.

The manifold 21 includes a manual choke 35 and an automatic choke 36 for manual and automatic control of the back pressure on fluid returning from the well through the manifold to the tank, for providing either manual or automatic control of the fluid pressure within the tubing strings in the well, which is particularly important to certain well procedures in which it is preferred that fluids be neither displaced into formations communicating with the well or produced from such formations.

A direct-reading pressure gauge 40 is connected in the input line 30 for indicating the'pressure of liquids being supplied to the well through the manifold 21. The pressure recorder 34 communicates I with input and return line portions of the manifold by lines 41 and 41a, respectively. The lines 41 and 41a are connected together by a two position, three-way valve 41b so that the recorder is selectively communicated with either the input or return pressure in the manifold. A flowmeter 42 included in the input line 30a is connected with the panel 33 by a conductor 42a for measuring and indicating the flow rate from the tank 22 to the manifold.

The manifold 21 includes a conduit line 43 connected at one end to the input line 30a and at the other end to a discharge-return line 430 leading to a suitable lubricator or chamber 44 which has a removable pressuretight end cap 45 to permit well tools to be inserted into and removed from the lubricator. The lubricator is connected into the flow line 240 connected to the tubing 24 so that a well tool is pumped from the lubricator through the flow line into the tubing in the well and returned from the well tubing through the flow line into the lubricator. The line 43 has a valve 50 for controlling flow therethrough. A first connector line 51 having a valve 52 therein is connected with the line 43 between the valve 50 and the line 43a. A second connector line 53 having a valve 54 therein is connected with the line 43 between the valve 50 and the input line 30a, so that flow in the input line 30 is directed into either the line 43 or the line 53. The connector lines 51 and 53 are connected into opposite ends of a third connector line 55 having a valve 60 therein. A discharge-return line 61 of the manifold is connected at one end with the lines 53 and 55 between the valves 54 and 60 and at its other end with a suitable lubricator or chamber 62 which is connected to the flow 25a connected the the well tubing 25. The lubricator has a removable pressure tight end cap 63 for sealing its free end, through which well tools are inserted into and removed from the lubricator and the flow line with which it is connected.

A return or discharge conduit line 64 of the manifold is connected at one end with the lines 51 and 53 between the valves 52 and 60 and at its other end with branch lines 64a and 64b which are in turn connected to each other and to the discharge line 32 which is connected into the usual liquid gas separator 32a. The line 32b connects the separator with the storage tank 22. The branch line or portion 64a has the automatic choke 36 connected therein and the branch line or portion 64b has the manual choke 35 connected in it. A flow meter 65 is connected in the line 64 and to the readout panel 33 by a conductor 65a for measuring and indicating the rate of return flow from the manifold into the return discharge line 32 to the tank 22. The branch return line portions 64a and 64b include valves 70 and 71, respectively, so that flow in the line 64 to the line 32 is diverted through either branch to utilize either the manual or the automatic choke, as will be explained hereinafter.

The line 51 and its valve 52, and the line 55 and its valve 60, together with line 53 and its valve 54, thus provide flow conduit means for flow connecting the input line 30a and conduit line 43 with the flow line 24a and tubing string 24, and for connecting the tubing string 25 and flow line 25a and the return line 61 with the return conduit line 64 with discharge line 32 and the storage tank 22. Similarly, as shown in FIG. 2, the input line 30a may be connected by way of the connector line 53 with the line 61, the flow line 25a and the tubing 25, while the tubing 24 and flow line 24a are connected by way of the connector line 51 with the return conduit line 64 and discharge line 32 and tank 22, to provide reverse fluid circulation through the system.

A conduit 72 connected with the automatic choke 36 has branch portions 72a and 72b extending from a two-position three-way valve 74 to the lines 64 and 30, respectively, whereby the choke is selectively operable responsive to either manifold input or return fluid pressure present in such lines.

One form of the automatic choke 36 is shown in FIGS. 6 and 7 and includes a tubular body 80 having a lateral inlet port 81 and a longitudinal discharge bore or passage 82 at one end. A plunger type valve assembly 83 including a valve member 84 and a stem 85 having a bore 85a is disposed within the choke body 80 for longitudinal movement relative to an annular valve seal 90 secured within the body between the inlet port 81 and the discharge passage 82 for controlling the fluid flow through the choke. The valve plunger assembly is biased toward a closed position by a spring 91 and toward an open position by the force of control fluid pressure supplied through the conduit 72 from the input or return lines of the manifold into an annular chamber 92 in the choke body around the valve stem. The control fluid pressure acts around the valve stem on an annular area defined by spaced ring seals 93 and 94 within the choke body which seal around portions of the valve stem of different diameters.

The choke 36 is connected in the branch or return line portion 64a of the manifold 21 on the downstream side of the valve 70 so that when the valve 71 in the branch line portion 64b is closed and the valve 70 is open, returning fluid from the line 65 is diverted through the valve 70 into the inlet port 81 of the automatic choke. The return fluid flows through the choke body between the seat and valve member through the passage 82 into the portion of the branch line 64a downstream of the choke. The fluid flows through the discharge line 32 of the manifold and the separator 32a to the tank 22. The choke is adjusted by compressing the spring 91 to maintain a predetermined back pressure through the manifold into the well system. The choke performs a regulating function by constantly adjusting the back pressure .responsive to the fluid pressure in either the input line 300 or the return line 64 of the manifold.

The well system 23, including the manifold 21, is useful for a number of procedures in a well involving both pumping fluids through the well and also displacing well tools into and returning them from a well. By way of example, one particular method which may be carried out in the well system is the pumping of a well tool from the lubricator 44 through the flow line 24a and the tubing string 24 into the landing nipple 28 at the lower end of the tubing string.

Assuming that the well is producing formation fluids, it is preferred that the well be first shut-in or "killed to establish substantially static or stable conditions within the well. The usual methods of providing a hydrostatic pressure at the bottom of the well equal to the formation pressure are employed, which includes filling the tubing strings 24 and 25 with a weighting liquid such as oil or water of sufficient density to overcome formation pressure at the bottom of the well. Also, a less dense liquid for only partially overcoming formation pressures may be used in conjunction with holding a back pressure on the well at the surface to stabilize the well and shut it in. The flow pattern illustrated by the arrows in FIG. 1 is used for circulating the fluid through and filling the tubing strings. For fluid flow into the tubing string 24 of the well from the tank 22 through the manifold and the flow line 244, the valves 52 and 54 in the connector lines 51 and 53, respectively, are closed. The valve 50 in the line 43 is open so that fluid pumped from the tank 22 through the line 30 by the pump 31 is delivered into the manifold input line 30a from which it flows through the line 43, the open valve 50, and into the line 43a. The closed valves 52 and 54 restrict the flow to the line 43 so that it must pass directly into the line 43a connected with the lubricator 44. The fluid flows through the lubricator and flow line 240 into and downwardly in the tubing string 24. At the lower end of the tubing string 24 the fluid crosses over in the device 27 into the lower end of the other tubing string 25.

For return through the manifold of the fluid from the well in the tubing string 25 and flow line 25a, the valve 60 in the connector line 55 is open and since the valves 52 and 54 are already closed, as explained above, fluid from the line 61 is restricted to flow through the connector line 55 into the return line 64. The fluid flows upwardly in the tubing string 25 through the flow line 25a into the lubricator 62 from which the fluid enters the line 61. The fluid flows from the line 61 into the connector line 55 and through the open valve 60 into the return line 64 and the line 32 to the tank 22.

During the fluid circulation for shutting-in the well, the manual choke 35 is used until the production fluids are circulated out and replaced with the weighting liquid. The production fluids generally include entrained gases which often cause the flow rates and pressures to vary substantially at the surface, possibly beyond the range of the capacity of the automatic choke to maintain the well under control. Thus, in order to minimize the possibility of blowouts with resulting fires, equipment damage, and fluid losses, the manual choke 35 is operated in the system by closing the valve in the branch return line portion 640 and opening valve 71 in the branch line portion 64b so that all of the returning fluids in the line 64 are diverted from the return line 64 through the line 64b and the manual choke. The fluids flow from the line 64b into the discharge line 32 passing to the separator 320 with the liquids being returned to the tank 22.

The weighting liquid is circulated from the tank 22 through the manifold into the well and formation fluid is produced until the formation fluids have been completely displaced from the tubing strings 24 and 25 replaced with the weighting liquid for establishing the desired pressure within the tubing strings at their lower ends to stabilize the well and to prevent production fluids from flowing from the well formations through the casing perforations 23a into the well.

While displacing the production fluids from the tubing strings by the weighting liquid, the manual choke 35 is adjusted in the usual manner to maintain sufficient back pressure on the well through the manifold to keep the well under control. The readout panel 33 and pressure recorder 34 provide visual indications of both the pressures and flow rates in the manifold input line 30a and the return line 64 so that the operator may constantly observe the flow conditions in both the fluid supply to the well and fluid return from the welland make the compensating adjustments in the back pressure by manipulation of the manual choke.

After the well is stabilized so that the desired conditions are established in the well, a well tool is pumped from the lubricator 44 through the tubing string 24 into the landing nipple 28 at the lower end of the tubing. The well tool is connected in a tool train including pumpable seal units and related equipment such as illustrated and described at Pages 3779-3781, The Composite-Catalog of Oil Field Equipment and Services, 1966-67 Edition. The cap 45 on the lubricator 44 is removed, the tool train is inserted into the lubricator, and the cap is replaced. The valves of the manifold remain as adjustedfor circulating the weighting liquid into the well through the flow line 24a and returning it through the flow line 25a. The liquid used for pumping the tool train into the well, which preferably is the same as the weighting fluid, is circulated from the tank 22 by the pump 31 through the lines 43 and 43a of the manifold into the lubricator behind the tool train, applying a pressure differential across the tool train forcing it from the lubricator through the flow line 24a into the tubing string 24. Since the well system is filled with liquid, the movement of the tool train from the lubricator through the flow line and tubing string displaces liquid in advance of the tool train through the flow line 24a, the tubing string 24, the crossover 27, and the tubing string 25 to the surface. The fluid returns to the manifold through the flow line 25a and the lubricator 62 and through the already described paths through the manifold back to the tank 22.

During the pumping of the tool train into the well .it is preferred that production of formation fluids into the well through the perforations 23a and displacement of the circulating liquid outwardly into the formation through such perforations be held to a minimum. Thus, during the circulation of the liquid to move the tool train, the automatic choke 36 is utilized to impose a controlled back pressure on the well which maintains optimum bottom hole well conditions. The automatic choke is place inoperation in the system by closing the valve 71 in the return branch line portion 64b and opening the valve 70 in the branch line portion 64a so that the returning fluid is directed through the automatic choke. The proper setting for the automatic choke is determined in the usual manner so that the choke controls the back pressure within a predetermined range for achieving optimum bottom hole well conditions which minimize fluid movement between the formation and the well during the liquid circulation procedure for moving the tool train from the surface to the desired position in the tubing string. As already explained, the setting of the automatic choke is accomplished by adjustments of the choke spring 91 for establishing the desired back pressure. The choke is preferably communicated with the return fluid pressurethrough the line 72a by adjustment of the valve 74 so that the pressure of the return fluid is monitored for maintenance of the desired back pressure by the choke. When a pressure increase in the return fluid is communicated through the line 72a into the chamber 92, the valve assembly is forced farther open against the spring 91 so that the back pressureis decreased. vWhen the pressure in the returning fluid decreases sufficiently, as sensed in the chamber 92, the spring 91 forces the valve assembly back toward its seat, thus restricting flow through the valve until the forces of the spring and the control fluid pressure reach a balanced condition. in this manner, the position of the valve member of the choke fluctuates in response to the pressure communicated to it so that it regulates the back pressure within the desired predetermined range.

The tool train is pumped downwardly in the tubing string 24 until the well tool is seated in the landing nipple 28 at the lower end of thetubing string. Generally, the tool is then left in the landing nipple to discharge its particular function.

The elements of the tool train are disengaged from the well tool in the landing nipple 28 and are displaced back to the surface through'the tubing string 24 and the flow line 24a into the lubricator 44 for removal from the well system. To pump the tool train back to the surface, the circulating fluid flow pattern is reversed so that the fluid is pumped into the well through the flow line 25a, as shown by the arrows in FIG. 2. The flow reversal is effectedby closing the valve 50 in the line 43, opening the valves 52 and 54 in the'connector lines 51 and 53, respectively, and closing the valve 60 in the connector line 55. The closed valve 50 diverts the fluid pumped into the input line 30a into the line 53 through which it flows to the line 61 since the closed valve 60 prevents flow into the line 55. The fluid is supplied through line 61 and the lubricator 62'into'the flow line 25a through which it flows into and downwardly through the tubing string 25. The fluid crosses over into the tubing string 24 in the connection 27 so that the pressure is applied below the tool train for displacing the tool train upwardly through the tubing string 24. The fluid in the tubing string 24, the flow line 24a, and the lubricator 44 is displaced in advance of the upwardly moving returning tool train. The return flow follows the paths shown in FIG. 2, exiting from the lubricator 44 to the manifold through the line 430 the connector line 51 in which it flows through the open valve 52 into the return line 64. The return fluids follow the already described path through the automatic choke 36 in the branch line portion 64a back through the separator into the tank 22. The fluid is circulated until the tool train hasbeen returned into the lubricator 44. The pumping is then stopped, the pressure cap 45 on the lubricator is removed, and the tool train withdrawn. The pressure cap is replaced for such further fluid circulation or other well procedures as may be desired. During the return of the tool train to the surface the automatic choke 36 controls the back pressure on the system as already described.

The procedures already described for pumping a tool train from the lubricator 44 into the landing nipple at the lower end of the tubing string 24 are equally adapted to pumping a tool train from the lubricator through the flow line 25a and'the tubing string 25 to the lower end of the tubing string 25. it will be evident that during the pumping of the tool train into the tubing string 25 the fluid input is through the lubricator 62 behind the tool train so that the flow pattern of FIG. 2 is employed. The return of the tool train from the tubing string 25 into the lubricator 62 is carried out by using the fluid flow pattern of FIG. 1 to pump the fluid downwardly into the tubing string 24 and through the crossover device 27 into the tubing string 25 below the tool train.

The automatic choke may be controlled in response to the input fluid pressure by setting the valve 74 to communicate the fluid pressure from the line 30a through the line 72b into the line 72 leading into the control fluid chamber 92 of the automatic choke. Since the input pressure required to overcome friction losses-in circulating the fluid through the input leg of a well system, the tubing string 24 in the well 23, does not increase the pressure at the bottom of the hole and is thus not a factor in the back pressure held on the well, a correction factor is required which disregards the friction losses in such input leg when operating the automatic choke responsive to input pressure. in contrast, the friction losses in the return leg of the well flow system requires pressure at the bottom of the well which is imposed on the well formation and is a factor in the back pressure held on the well. if the tubing strings 24 and 25 have substantially identical frictional loss characteristics this correction factor is provided by use of an automatic choke having a valve assembly which has an effective area on its valve stem 85 within the control fluid chamber 92 between the ring seals 93 and 94 equal to substantially one-half the effective area in a choke designed for use in response to the fluid pressure on the return side of the system. If the friction losses in the two legs are not equal, the correction factor employed in adjusting the system is such as to disregard the friction losses in the input leg of the system.

The specific compact portable form of the manifold 21 shown in FIGS. 3-5, includes the same functional components denoted by the same reference numerals as already described and illustrated in schematic form in FIGS. 1 and 2. The portable manifold is supported on a skid 100 comprising a pair of spaced runners 101 secured together along opposite end portions by lateral members 102 and by plurality of lateral intermediate platform members 103. The manifold is secured by U-bolts 104 to channel shaped mounting brackets 105 secured on the members 103. As best seen in FIG. 4, the manifold is supported along one side on a pair of spaced brackets 105 secured with the return line 64 and the branch line portion 64b. Similarly, the manifold is supported along the other side on the skid by a pair of spaced brackets 105 secured with the supply return line 43a and the input line 30a. The supply return line 61 also is supported on one of the brackets 105. The input and return lines 300 and 32 and the supply return lines 43a and 61 are provided, respectively, with identical flanged couplings 30b, 32c, 43b, and 610, respectively, for connecting the manifold into a well system as illustrated in FIGS. 1 and 2. The portable manifold is installed in the well system by connecting its flange couplings 43b and a with lines lading to the lubricators 44 and 42, respectively, and its input and return line couplings 30b and 320 with lies to the pump 31 and the separator 32a, respectively. To conserve horizontal space, enhancing the portability of the skid mounted manifold, an over-and-under arrangement of the components as illustrated in FIGS. 3-5 has been employed. Generally, the manual and automatic chokes along with the branch return line portions in which they are connected are supported at a lower level on the skid while the connector lines 51, 53, and 55 along with portions of the lines 43, 61 and 64 are supported in close proximity at an upper level so that all the components of the manifold are nested together as a compact assembly which is readily movable between well locations. The readout panel 33 and pressure recorder 34, illustrated schematically in FIG. 3, are connected to and function with the manifold as already described.

Referring to FIGS. 6 and 7 the automatic choke 36, already broadly described, has the choke body 80 which includes a spring housing section 120 enclosing the control spring 91, a cylinder section 121 including the control fluid pressure chamber 92, a valve housing section 122 in which the valve member 84 is movably disposed, and a seat and coupling section 123 which supports the annular valve seat 90 at its inward end and provides connection means at its outward or downstream end for a downstream portion of the branch line 64a into the choke.

The valve member of the choke is biased by the spring 91 toward a closed position at which an internal conical seat surface 90a of the seal 90 is engaged by a conical head seat surface 841: on the valve head member 84. The spring 91 is housed within the choke body section 120 and is compressed between an adjusting nut 124 and an external annular flange 125 on the 'valve stem 85. The adjustingnut has a handle 126 for rotating the nut to vary the compression of the spring. The nut has a blind bore 127 for receiving an end portion of the valve stem which telescopes into the nut when the valve member moves to an open position and when the spring is compressed to increase the force required to open the valve member. The body section 120 has a lateral port 131 so that the spring 91 and portion of the valve stem within the spring housing section operate under atmospheric pressure. A pair of ring seals 132 supported by the adjusting nut seal between the stem and the nut.

The valve member is biased open by control fluid communicated into the annular chamber 92 through the tubing 72 connected into a lateral internally threaded bore 140 in the body section 121 by a coupling 141. The spaced ring seals 93 and 94 carried by the cylinder section 12] of the choke body seal with the longitudinal valve stem portions a and 85b, respectively, to define the chamber 92. The valve stem portion 85b is smaller in diameter than the stem portion 850 so that an annular surface 100 is provided on the valve stem facing the valve seat exposed to control fluid pressure within the seat 92 for biasing the valve assembly away from the valve seat toward open position. When the force of the control fluid pressure within the chamber 92 acting on the annular surface 100 of the valve stem exceeds the force exerted by the spring 91 on the valve stem flange 125, the valve stem is forced toward the spring moving the valve member 84 to a spaced position from the valve seat and opening the choke. Fluid entering the choke body through the lateral port 81 flows between the valve head member surface 84a and the valve seat 90a and through the bore 82 of the valve seat and coupling member into the downstream portion of the branch line portion 64a.

The valve assembly bore 850 provides a flow passage throughout the length of the valve assembly so that the pressure within the choke body downstream of the valve member 84 is communicated through the valve assembly into the bore 133 of the nut 124 along the outer end portion of the valve stem to equalize the pressures acting on the opposite end portions of the valve assembly.

The line of sealing between the valve head member face 84a and the valve seat face 900 is the same diameter as the line of sealing of the ring seals 94 with the valve stem so that the forces resulting from the pressure around the valve stem and the valve member 84 within the choke body between the seals 94 and'the line of engagement of the faces 84a and 90a are balanced and do not bias the valve stem and valve member toward either closed or open position. Similarly, the line of sealing between the faces 84a and 90a is the same diameter as the line of sealing of the ring seals 132 with the valve stem within the adjusting nut so that balanced forces are imposed on the valve stem and member along opposite end portions resulting from the pressure within the choke downstream of the valve member as communicated through the flow passage 85a of the valve assembly. Thus, the downstream pressure in the choke does not tend to bias the valve assembly toward either closed or open position. The net forces affecting the opening and closing of the choke are therefore substantially limited to the force applied by the spring 91 to the valve stem and the opposite force on the stem surface resulting from the controlled fluid pressure within the chamber 92 communicated from either the return conduit line 64 or the input conduit line 30a.

It will be recognized that other forms of pressure control means than the choke 36 may be used to provide a controlled back pressure on the well system responsive to the input or return fluid pressure.

The well system 20 has been described and illustrated as including the tubing strings 24 and 15 along with the crossover connection 27 so that fluid is supplied into and returned from the well through an exclusive U-shaped flow path in the well. The desired U-shaped flow pattern may also be obtained by other structural arrangements within a well, such as by the use of a single tubing string communicating at a desired location along its length with the tubing-casing annulus defined within the casing of the well around the tubing string. The tubing string functions as either an input or a return leg, and, similarly, the tubing-casing annulus serves as either an input or a return leg. Fluid may flow in either direction as already explained. In such a well arrangement, tools are pumped into and out of the well in the single tubing string from a lubricator connected at the surface with the tubing string. The tubing string serves as the input flow passage and the tubing-casing annulus as the return flow passage during the pumping of the well tools into the well. The circulation pattern is reversed so that the tubing-casing annulus functions as the input flow passage with the tubing string serving as the return flow passage to pump the well tool back through the tubing string into the lubricator at the surface.

It will now be seen that a new and improved well system and method for pumping well tools into and out of a well and performing other well servicing procedures has been described and illustrated.

It will be further seen that the well system includes supply and return flow passages connected with a surface manifold for supplying fluid under controlled flow conditions to the well flow passages for flow in either direction through such passages.

It will also be seen that the well system includes means providing input and return well flow passages, a manifold connected with such flow passages for controlling fluid flow conditions and direction in the well flow passages, pump means for supplying fluid under pressure to the manifold, a separator for segregating liquids and gases in the fluids returning from the manifold and a reservoir tank for storing returned liquids from the manifold for reinjection into the flow passages of the well system.

It will also be seen that a new and improved surface manifold has been described and illustrated for supplying well fluid to a well flow passage system under controlled conditions and for flow in either' direction through such well flow passages.

It will be further seen that the manifold includes manual and automatic choke means for imposing a controlled back pressure in fluids flowing in the manifold.

It will additionally be seen that a preferred form of the surface manifold is a compact portable unit adapted to be readily moved from one well location to another.

It will also be seen that a new and improved automatic choke has been described and illustrated operable responsive to fluid pressure communicated to the choke from either the line through which the choke controls flow-conditions or from a pressure source independent of such line. it will be further seen that a new and improved method of circulating fluids in a well has been described and illustrated which includes supplying fluids to and returning fluids from a well without either producing formations fluids from the well or forcing the circulating fluids into formations communicating with the well.

It will be further seen that in accordance with one aspect of the invention production is terminated and the well is stabilized by filling the well witha weighting fluid for partially or completely counterbalancing well pressure to prevent production fluids flowing into the well, and a well tool is introduced into the well by pumping the tool through one flow passage in the well while returning fluid within the well in advance of the tool to the surface through another flow passage in the well while the return flow pressure is maintained at a value which produces bottom hole pressure conditions in the well which minimize flow between the well and the formation surrounding the well.

FIGS. 1A and 2A illustrate an alternate simplified form of fluid circulation control manifold 21A which may be used in situations where flow conditions, and in particular pressure conditions, permit the use of valves, such as three-way valves which are normally employed at lower pressures than the valves of the type shown in the manifold 21 in FIGS. 1 and 2. With the exception of the flow direction control features of the manifold 21A, all other features of the manifold and of a well system with which it is used are identical to those shown in FIGS. 1 and 2 and already described, and thus components common to both systems and manifolds are referred to by the same reference numerals as used in FIGS. 1 and 2. A threeway valve 200 is connected to the discharge end of the input line 30a downstream of the pump 31 and the flowmeter 42, shown only in FIGS. 1 and 2. First and second connecting conduit lines 201 and 202 are each connected at one end into the valve 200 so that the valve selectively directs fluid from the input line into either of the connecting lines. Asecond threeway valve 203 is connected with the other end of the first and second connecting lines and with the input end of the return line 64 which leads to the manual and automatic chokes 36 as shown in FIGS. 1 and 2. The valve 203 selectively directs fluid into the return line from either of the connecting lines. The discharge-return line 43a is connected at one end into the lubricator 44 and at the other end to the first connecting line 201. Similarly, the discharge-return line 61 is connected at one end to the lubricator 62 and at the other end to the second connecting line 202.

When the valves 200 and 203 are positioned as shown in FIG. 1A fluid delivered to the manifold through the input line is directed by the valve 200 into the first connecting line 201. Theinput fluid flows through the first connecting line into the conduit line 43a. From the line 43a the fluid flows through the lubricator 44 into the well system as shown in FIG. 1. The fluid returning from the well system flows through the lubricator 62 and the conduit line 61 into the second connecting line 202. It flows through the valve 203 into the return line 64 following the already described paths back to the tank 22 as shown in FIG. 1. Flow in the opposite direction through the manifold and the well system is obtained by positioning the valve 200 and 203 as shown in FIG. 2A. The input fluid flows through the valve 200 into the second connecting line 202 from which it flows to the lubricator 62 through the conduit line 61. The return fluid from the well system flows from the lubricator 44 through the conduit line 430 into the first connecting line 201. The fluid flows from the first connecting line through the valve 203 into the return line 64 and on to the tank 22 through either of the chokes, as already discussed.

It will now be seen that where flow conditions permit a more simplified manifold may be employed utilizing a reduced number of valves for controlling the direction of flow of the input and return fluids through the manifold.

The foregoing description of the invention is explanatory only, and changes in the details of the construction illustrated.

may be made by those skilled in the art, within the scope of the appended claims, without departing from the spirit of the invention.

What is claimed and desired to be secured by Letters Patent l. A well flow system comprising: means extending into a well from the surface providing first and second passages therein; means within said well providing fluid communication between said first and said second flow passages permitting fluid circulation through said well from the surface end thereof; and manifold means communicating with said surface ends of said flow passages of said well, said manifold means including an input flow passage portion connected to a source of fluid pressure and a return flow passage portion having means for imposing a predetermined back pressure on fluid in said return flow passage portion, and means for selectively communicating either one of said flow passages of said well with one of said input and return passage portions and the other of said flow passages with the other of said input and return passage portions.

2. A well flow system as defined in claim 1 wherein said means for imposing said back pressure includes fluid choke means providing a variable flow restriction in said return flow passage portion of said manifold means.

3. A well flow system as defined in claim 2 wherein said choke means is an automatic choke selectively operable responsive to either the pressure at which fluid is supplied to said manifold means or the pressure of fluid flowing in said return flow passage portion of said manifold means.

4. A well system as defined in claim 3 including a manual choke disposed in parallel fluid flow relationship with said automatic choke and valve means for selectively directing return fluid flow through either of said chokes.

5. A well system as defined in claim 4 including fluid pressure and flow rate monitoring means for determining input and return fluid flow rates and pressures in said well system.

6. A well system as defined in claim including pump means for supplying fluid under pressure to said manifold means, fluid reservoir means communicating with said pump means for storing fluid for injection into said well system and for receiving fluid from said system, and separator means communicating with said manifold means and said fluid reservoir means for segregating fluids and gases returning from said well flow passages through said manifold means.

7. A well system as defined in claim 4 including a pressure tight chamber communicating with said manifold means and one of said well flow passages for insertion and removal of well tools pumped into and out of said well through said flow passage by fluid introduced into and returned from said well through said manifold means.

8. A well flow system as defined in claim 1 wherein said input flow passage portion and return flow passage portion of said manifold means comprises: an input line connected to said source of fluid pressure; a return line; a first connecting line from said input line to said return line; a second connecting line from said input line to said return line in parallel flow relationship with said first line; at least two spaced valves in said first connecting line; at least two spaced valves in said second connecting line; a first discharge-return line connected at one end into said first connecting line between said spaced valves in said line and at the other end to one of said well passages; a second discharge-return line connected at one end into said second connecting line between said spaced valves in said line and at the other end to said other well passage; and wherein choke means is connected in said return line downstream of the connection of said return line into said first and second connecting lines.

9. A well system as defined in claim 8 wherein said choke means includes an automatic choke having a control fluid chamber selectively communicable with said input line and said return line for selectively operating said choke responsive to fluid pressure in either said input or said return line for imposing a controlled back pressure on said well flow passages through said manifold means.

10. A well system as defined in claim 9 including a manual choke connected in parallel flow relationship with said automatic choke in said return line, flowmeter means in said input line, flowmeter means in said return line, fluid pressure measuring means in said input line, and fluid pressure measuring means in said return line.

11. A well system as defined in claim 9 wherein said automatic choke comprises: a body having a bore and an inlet to said bore communicating with one portion of said return line and an outlet from said bore communicating with another portion of said return line; an annular valve seat member supported in said bore of said body between said inlet and said outlet; a tubular valve stem slidably supported within said bore of said body for longitudinal movement therein; an annular valve member supported on said valve stem and movable therewith between engagement with said valve seat member for closing off flow through said choke body between said inlet and said outlet and spaced from said valve seat member for permitting fluid communication between said inlet and said outlet; and means providing a first seal within said choke body around said valve stem; means providing a second seal within said choke body around said valve stem spaced along said valve stem from said first seal; the line of sealing engagement of said first seal with said valve stem being less than the line of sealing engagement of said second seal with said valve stem whereby fluid pressure applied to said valve stem between said first and second seals within said choke body biases said valve stem away from said seat member for moving said valve member to a spaced position from said valve seat member for allowing fluid communication between said inlet and said outlet responsive to said fluid pressure within said bore between said seals; conduit means connected into said choke body between said first and said second seals for supplying control fluid pressure to said choke; and spring means on said valve stem for biasing said valve stem and said valve member toward said valve seat member for moving said valve member into engagement with said valve seat member for shutting off fluid communication between said inlet and said outlet when said control fluid pressure decreases below a predetermined value.

12. A well flow system for a well having a plurality of conduits extending into said well from the surface and in fluid communication with each other in said well, said system including: a fluid flow control manifold for supplying fluid to and receiving fluid from said conduits of said well comprising: an input line connected to a source of fluid pressure; a return line to said source of fluid pressure; a first connecting line from said input line to said return line; a second connecting line from said input line to said return line in parallel flow relationship with said first line; at least two valves at spaced locations in said first connecting line; at least two valves at spaced locations in said second connecting line; a first dischargeretum line connected at one end to one of said conduits in said well and at its other end into said first connecting line between said spaced valves in said line; a second discharge-return line connected at one end to another of said conduits in said well and at its other end into said second connecting line between said spaced valves in said line; and choke means in said return line downstream of the connection of said return line into said first and second connecting lines for maintaining a back pressure in said return line upstream thereof.

13. A well flow system and fluid flow control manifold as defined in claim 12 wherein said return line includes at least two parallel flow portions, automatic choke means in one of said return line parallel portions, fluid pressure communicating means between said automatic choke means and said input and return lines for selectively communicating said automatic choke means with either of said input and return lines, manual choke means in the other of parallel portion of said return line, and valve means in said return line for selectively directing fluid in said return line through either of said parallel portions of said return line through either said automatic choke or said manual choke.

14. A well flow system and fluid flow control manifold as defined in claim 13 including flowmeter means in said input line, flowmeter means in said return line, fluid pressure measuring means in said input line, and fluid pressure measuring means in said return line.

15. A well flow system and fluid flow control manifold as defined in claim 13 including portable platform means, bracket means connected between said platform means and a portion of said manifold lines for supporting said manifold in a readily movable status, and coupling means on each of said input, return, and discharge-return lines for releasably connecting said manifold with said conduits providing input and return well flow passages and with said fluid pressure source.

16. A well flow system and flow control manifold as defined in claim 15, wherein said portions of said connecting lines and said valves connected therein are supported at an upper level above said platform means and said manual and automatic chokes and portions of lines connected therewith are supported therebelow at a lower level whereby the length and width of said manifold and said platform means are minimized.

17. A well flow system for a well having a pair of flow conductors extending from the surface into said well and flow connected near their lower ends, including: a fluid flow control manifold for supplying fluid to and receiving fluid from said flow conductors comprising: an input line connected to a source of fluid pressure; a first discharge-return line connected to one of said flow conductors; a conduit line connected at one end of said input line and at the other line to the other end of said first discharge-return line; a valve in said conduit line; a first connector line connected at a first end into said conduit line between said valve therein and said first discharge-return line; a valve in said first connector line; a second connector line connected at a first end into said conduit line between said valve therein and said input line; a valve in said second connector line; a third connector line connected at one end to a second end of said first connector line and connected at the other end to a second end of said second connector line; a valve in said third connector line; a second discharge-return line connected at one end to the other of said flow conductors and at its other end connected into said second and third connector lines between said valves therein; a return-line connected into said first and third connector lines between said valves therein; said return line including first and second parallel branch line portions, each of said branch line portions having a valve connected therein for controlling flow therethrough; a manual fluid flow choke in said first return branch line portion downstream of said valve therein; an automatic fluid flow choke connected in said second return branch line portion downstream of said valve therein; and fluid pressure communication means connected between said automatic choke and said return line for controlling said automatic choke responsive to fluid pressure in said return line.

18. A fluid flow control manifold as defined in claim 17 including fluid pressure communication means connected between said automatic choke and said input line, said automatic choke being selectively operable responsive to fluid pressure in either said input line or said return line.

19. A well fluid flow control system for supplying fluid to and receiving fluid from a pair of flow conductors extending from the surface into said well and flow connected at their lower ends comprising: an input line connected to a source of fluid pressure; a return line; a first connecting line from said input line to said return line; a second connecting line from said input line to said return line in parallel flow relationship with said first line; valve means associated with said connecting lines for selectively directing fluid from said input line through either one of said connecting lines and for selectively directing fluid from the other one of said connecting lines into said return line; a first discharge-return'line connected at'o'ne end to one of said well flow conductors at the surface and at its other end into said first connecting line for conducting fluid between said manifold and said well flow conductors; a second discharge-return line connected at one end to the other of said well flow conductors at the surface and at its other end into said second connecting line for conducting fluid between said manifold and said well flow conductors; and choke means in said return line for imposing a predetermined back pressure on fluids flowing in said flow conductors and said manifold upstream of said choke means.

20. A well fluid flow control system for supplying fluid and receiving fluid from a pair of flow conductors extending from the surface into said well and flow connected at their lower ends comprising: an input line connected to a source of fluid pressure; a return line; a first connecting line from said input line to said return line; a second connecting line from said input line to said return line in parallel flow relationshipwith said first line; first valve means at the juncture of said input line with said first and second connecting lines for selectively communicating said input line with either of said first connecting line and said second connecting line; second valve means at the juncture of said return line with said first and second connecting lines for selectively communicating said return line with either of said first connecting line and said second connecting'line; a first discharge-return line connected at one end into said first connecting line and connected at its other end to a lubricator connected to one of said well flow conductors; a second discharge-return line connected at one end into said second connecting line and connected at its other end to a lubricator connected to the other of said well flow conductors; and choke means in said return line downstream of the connection of said return line with said first and second connecting lines maintaining a back pressure in said return line upstream of said choke means.

21. Apparatus for servicing a well having a plurality of well conduits extending into said well which comprises in combination: support means; manifold means comprising a plurality of conduitmeans arranged on said support means; one end of each of said conduit means extending from said support means and adapted to be connected to said well conduits extending into said well; each said conduit means being connected with lubricator means for inserting a well tool into one of said well conduits; a radius bend in at least one of each of said well conduits and conduit means; first and second connecting conduit means connected to said conduit means; and valve means in each of said connecting conduit means for opening and closing said connecting conduit means; one of said conduit means being adapted to be connected to pump means and-the other being adapted to be connected to tank means connected to said pump means; whereby a tool inserted into said lubricator means is pumpable through said conduit means and said conduits extending into said well.

22. Apparatus in accordance with claim 21 in which the support means is portable. v

23. Well apparatus which comprises: a plurality of well conduits extending into a well; portable support means; manifold means comprising a plurality of conduit means arranged on said support means; one end of each of said conduit means extending from said support means and releasably connected to one of said conduits extending into said well; each of said conduit means being connected with openable and closable lubricator means for inserting a'-well tool into at least one of said well conduits; a radius bend in at least one of each of said well conduits and conduit means; at least first and second connecting conduit means connecting said conduit means; pump means; tank means; one of said conduit means being releasably connected to said pump means and the other of said conduit means being releasably connected to said tank means; and means connecting said pump and tank means; whereby said support means, said conduit means, and said connecting conduit means maybe disconnected from said well conduits extending into said well and from said pump and tank means and connected to similar means on another well.

24. Apparatus for servicing a well having a plurality of well conduits extending into said well which comprises in combinationzsupport means; a plurality of conduit means arranged on said support means; one end of each of said conduit means extending from said support means and adapted to be connected to said well conduits extending into said well; the other end of each said conduit means being provided with openable closure means for inserting a well tool into said conduit means; a radius bend inat least one of each of said well conduits and conduit means; first and second branched conduit means having branches connected to said conduit means and said branched conduit means having a free end; and valve means in each of said branches for opening and closing the branches of said branched conduit'means; the free end of said branched conduit means being adapted to be connected to pump means and being adapted to be connected to tank means connected to said pump means; whereby a tool inserted into said conduit means is pumpable through said conduit means and said conduits extending into Said well.

25. Apparatus in accordance with claim 24 in which a radius bend is provided in each of said conduit means.

26. Apparatus in accordance with claim 24 in which a radius bend is provided in each of said well conduits.

27. Apparatus in accordance with claim 24 in which at least one of said branched conduit means is provided with a valve means adjacent the free end and past the branches thereof.

28. A system for use with a completion system in which there are two strings of tubing suspended in the well bore with means in said well fluidly connecting said strings for use with pump down tool equipment:

pump means for supplying hydraulic fluid under pressure;

a first conduit means connected to one of said tubing strings;

second conduit means connected to the other of said tubing strings;

means to selectively connect the outlet of said pump means to either of said first and second conduit means;

a connecting conduit between said first conduit means and said second conduit means with two valves therein;

a production conduit means connected to said connecting conduit between said valves, said production conduit means comprising a first conduit having a valve therein and a production flow choke downstream of such valve, and a second conduit in parallel with said first conduit and having a valve therein and means downstream of said valve to hold a selected back pressure, regardless of varying flow rate, on the one of said conduit means not connected to said pump means.

29. In combination with a well system having at least first and second interconnected tubing strings arranged therein to provide a circulation path of fluid down one tubing string and up the other tubing string, apparatus which comprises: a back pressure manifold connected to said two tubing strings and to fluid pumping and storage means; said back pressure manifold comprising a first conduit having means for connecting it to said pumping and storage means and to the first tubing string; a first flowmeter and pressure measuring means in said first conduit; a second conduit connected to said second tubing string and connected to said first conduit between said first flowmeter and pressure measuring means and the first tubing string; a third conduit having means for selectively connecting it in flow communication either to the first conduit intermediate the connection between the first and second conduits and the first tubing string or in separate flow communication to the second conduit; second flowmeter and pressure measuring means in said third conduit downstream from the means for selectively connecting it to said first conduit on the said second conduit; variable choke means in said third conduit downstream from said second flowmeter and pressure measuring means for holding pressure on one of said tubing strings to provide a desired rate of flow through said interconnected tubing strings; said third conduit having means for connecting it to said fluid pumping and storage means; and valve means in said first, second and third conduits between the points of connection of said conduits with each other for directing flow in either direction in said first and second tubing strings; said flowmeter and pressure-measuring means comprising means for determining the fluid flow rates and pressures of fluids flowing through said conduits for varying said choke means for controlling flow through said interconnected tubing strings.

30. Apparatus in accordance with claim 29 in which bypass means is provided in said third conduit for bypassing said choke means.

31. Apparatus in accordance with claim 29 in which the choke means is automatic.

32. Apparatus in accordance with claim 29 in which the choke means is manual.

33. The combination of claim 29 wherein said flowmeter and pressure-measuring means comprises recording means providing a written record of the fluid flow rates and pressures of the fluids flowing through the manifold conduits for use in varying the setting of the variable choke means for controlling flow through the interconnected tubing strings.

34. A well flow system comprising: means extending into a well from the surface providing first and second flow passages therein; means within said well providing fluid communication between said first and said second flow passages permitting fluid circulation through said well from the surface end thereof; and mainfold means communicating with said surface ends of said flow passages of said well, said manifold means including an input flow passage portion connected to a source of fluid pressure and a return flow passage portion having fluid choke means for imposing a predetermined back pressure on fluid in said return flow passage portion comprising an automatic choke selectively operable responsive to either the pressure at which fluid is supplied to said manifold means or the pressure of fluid flowing in said return flow passage portion, a manual choke disposed in parallel fluid fiow relationship with said automatic choke, and valve means for selectively directing fluid flow through either of said chokes, fluid pressure and flow rate monitoring means for determining input and return fluid flow rates and pressures in said system for controlling flow through said system by means of said choke means, and means for selectively communicating either one of said flow passages of said well with one of said input and return passage portions and the other of said flow passages with the other of said input and return passage portions.

35. A well flow system of the character set forth in claim 34 wherein said automatic choke comprises: a body having a bore and an inlet to said bore and an outlet from said bore with an annular valve seat member supported in said bore of said body between said inlet and said outlet; a tubular valve stem slidably supported within said bore of said body for longitudinal movement therein; an annular valve member supported on said valve stem and movable therewith between engagement with said valve seat member for closing off flow through said choke body between said inlet and said outlet and spaced from said valve seat member for permitting fluid communication between said inlet and said outlet; and means providing a first seal within said choke body around said valve stem; means providing a second seal within said choke body around said valve stem spaced along said valve stem from said first seal; the line of sealing engagement of said first seal with said valve stem being less than the line of sealing engagement of said second seal with said valve stem whereby fluid pressure applied to said valve stem between said first and second seals within said choke body biases said valve stem away from said seat member for moving said valve member to a spaced position from said valve seat member for allowing fluid communication between said inlet and said outlet responsive to said fluid pressure within said bore between said seals; conduit means connected into said choke body between said first and said second seals for supplying control fluid pressure to said choke; and spring means disposed between said valve stem and saidchoke body for biasing said valve stem and said valve member toward said valve seat member for moving said valve member into engagement with said valve seat member for shutting off fluid communication between said inlet and said outlet when said control fluid pressure decreases below a predetermined value.

36. A well flow system of the character set forth in claim 34 wherein said fluid pressure and flow rate monitoring means comprises: recording means providing a written record of such fluid pressure and flow rates of the fluids flowing in the system for use in varying the setting of said fluid choke means for controlling flow through the well flow passages.

37. A well flow system comprising: means extending into a well from the surface providing first and second flow passages therein: means within said well providing fluid communication between said first and second flow passages permitting fluid circulation through said flow passages in said well from the surface end thereof; manifold means communicating with such surface ends of said flow passages of said well and including: an input line connected to a source of fluid pressure; a return line; a first connecting line from said input line to said return line; a second connecting line from said input line to said return line in parallel flow relationship with said first line; at least two spaced valves in said first connecting line; at least two spaced valves in said second connecting line; a first discharge-return line connected at one end into said said second connecting line between said spaced valves in said line and at the other end to one of said well flow passages; a second discharge-return line connected at one end into said second connecting line between said spaced valves in said line and at the other end to said other well flow passage; variable choke means connected in said return line downstream of the connection of said return line into said first and second connecting lines and including: an automatic choke having a control fluid chamber selectively communicatable with said input line and said return line for selectively operating said choke responsive to fluid pressure in either said input line or said return line for imposing a controlled back pressure on said well flow passages through said manifold means; a manual choke connected in parallel flow relationship with said automatic choke in said return line; flowmeter means in said input line; flowmeter means in said return line; fluid pressure measuring means in said input line; and fluid pressure measuring means in said return line; said flowmeter means and said fluid pressure measuring means comprising means for determining input and return fluid flow rates and pressures in said system for controlling flow through said flow passages of said well passages by means of said choke means 38. A well flow system of the character set forth in claim 37 wherein said flowmeter means and said fluid pressure measuring means comprise recording means providing a written record of the fluid pressures and flow rates of the fluids flowing through the input line and return line for use in setting said variable choke means for controlling flow through the flow passages in the well.

39. A well flow system for a well having a plurality of a extending into said well from the surface and including: a fluid flow control manifold for supplying fluid to and receiving fluid from said conduits of said well and comprising an input line connected to a source of fluid pressure; a return line to said source of fluid pressure; a first connecting line from said input line to said return line; a second connecting line from said input line to said return line in parallel flow relationship with said first line; at least two valves at spaced locations in said first connecting line; at least two valves at spaced locations in said second connecting line; a first discharge-return line connected at one end to one of said conduits in said well and at its other end into said first connecting line between spaced said valves in said line; a second discharge-return line connected at one end to another of said conduits in said well and at its other end into said second connecting line between said spaced valves in said line; choke means in said return line downstream of the connection of said return line into said first and second connecting lines for maintaining a back pressure in said return line upstream thereof and comprising at least two parallel flow conduit sections; automatic choke means in one of said parallel flow conduit sections of said return line; fluid pressure communicating means between said automatic choke means and said input and return lines for selectively communicating said automatic choke means with either of said input line and said return line; manual choke means in another of said parallel flow conduit sections of said return line; and valve means in said return line for selectively directing fluid in said return line through either of said parallel flow conduit sections of said return line through either of said automatic choke or said manual choke; flowmeter means in said input line; flowmeter means in said return line upstream of said choke means; fluid pressure measuring means in said input line; and fluid pressure measuring means in said return line between said flowmeter means in said line and said choke means; said flowmeter means and fluid pressure measuring means comprising means for determining the fluid flow rates and pressures of fluids flowing through said conduits for controlling flow through the flow passages in the well by means of said choke means.

40. A well flow system of the character set forth in claim 39 wherein said flowmeter means and said fluid pressure measuring means comprise recording means providing a written record of the fluid pressures and flow rates of the fluids flow- 7 ing through said connecting lines of the manifold means for 2323 UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,608,631 Dated September 28, 1971 Inventor(s) Phillip S. Sizer and Harry E. Schwegman It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Column 1, line 47, for "or" read -as- Column 2, line 31, for "32a" (second occurrence) read --32b- Column 3, line 11, for "the' (first occurrence) read --to-- Column 5, line 53, for "place" read --placed- Column 7, line 32, for "a" read -61aline 33, for "lading" read -leading-- line 34, for "lies" read --lines-- Column 10, line 45, before "passages" read -flow Column 13, line 47, before "and" read --to-- Column 16, line 60, delete "said" (second occurrence) line 61, for "second" read -first- Column 17, line 15, for "a" (fourth occurrence) read --condui signed and sealed this 25th day of July 1972.

SEAL) ttest:

EDWARD M.FLETCHER,JR. ROBERT GOTTSGHALK Attesting Officer Commissioner of Patents 

1. A well flow system comprising: means extending into a well from the surface providing first and second passages therein; means within said well providing fluid communication between said first and said second flow passages permitting fluid circulation through said well from the surface end thereof; and manifold means communicating with said surface ends of said flow passages of said well, said manifold means including an input flow passage portion connected to a source of fluid pressure and a return flow passage portion having means for imposing a predetermined back pressure on fluid in said return flow passage portion, and means for selectively communicating either one of said flow passages of said well with one of said input and return passage portions and the other of said flow passages with the other of said input and return passage portions.
 2. A well flow system as defined in claim 1 wherein said means for imposing said back pressure includes fluid choke means providing a variable flow restriction in said return flow passage portIon of said manifold means.
 3. A well flow system as defined in claim 2 wherein said choke means is an automatic choke selectively operable responsive to either the pressure at which fluid is supplied to said manifold means or the pressure of fluid flowing in said return flow passage portion of said manifold means.
 4. A well system as defined in claim 3 including a manual choke disposed in parallel fluid flow relationship with said automatic choke and valve means for selectively directing return fluid flow through either of said chokes.
 5. A well system as defined in claim 4 including fluid pressure and flow rate monitoring means for determining input and return fluid flow rates and pressures in said well system.
 6. A well system as defined in claim 5 including pump means for supplying fluid under pressure to said manifold means, fluid reservoir means communicating with said pump means for storing fluid for injection into said well system and for receiving fluid from said system, and separator means communicating with said manifold means and said fluid reservoir means for segregating fluids and gases returning from said well flow passages through said manifold means.
 7. A well system as defined in claim 4 including a pressure tight chamber communicating with said manifold means and one of said well flow passages for insertion and removal of well tools pumped into and out of said well through said flow passage by fluid introduced into and returned from said well through said manifold means.
 8. A well flow system as defined in claim 1 wherein said input flow passage portion and return flow passage portion of said manifold means comprises: an input line connected to said source of fluid pressure; a return line; a first connecting line from said input line to said return line; a second connecting line from said input line to said return line in parallel flow relationship with said first line; at least two spaced valves in said first connecting line; at least two spaced valves in said second connecting line; a first discharge-return line connected at one end into said first connecting line between said spaced valves in said line and at the other end to one of said well passages; a second discharge-return line connected at one end into said second connecting line between said spaced valves in said line and at the other end to said other well passage; and wherein choke means is connected in said return line downstream of the connection of said return line into said first and second connecting lines.
 9. A well system as defined in claim 8 wherein said choke means includes an automatic choke having a control fluid chamber selectively communicable with said input line and said return line for selectively operating said choke responsive to fluid pressure in either said input or said return line for imposing a controlled back pressure on said well flow passages through said manifold means.
 10. A well system as defined in claim 9 including a manual choke connected in parallel flow relationship with said automatic choke in said return line, flowmeter means in said input line, flowmeter means in said return line, fluid pressure measuring means in said input line, and fluid pressure measuring means in said return line.
 11. A well system as defined in claim 9 wherein said automatic choke comprises: a body having a bore and an inlet to said bore communicating with one portion of said return line and an outlet from said bore communicating with another portion of said return line; an annular valve seat member supported in said bore of said body between said inlet and said outlet; a tubular valve stem slidably supported within said bore of said body for longitudinal movement therein; an annular valve member supported on said valve stem and movable therewith between engagement with said valve seat member for closing off flow through said choke body between said inlet and said outlet and spaced from said valve seat member for permitting fluid communication between said inlet and said outlet; and means providing a first seal within said choke body around said valve stem; means providing a second seal within said choke body around said valve stem spaced along said valve stem from said first seal; the line of sealing engagement of said first seal with said valve stem being less than the line of sealing engagement of said second seal with said valve stem whereby fluid pressure applied to said valve stem between said first and second seals within said choke body biases said valve stem away from said seat member for moving said valve member to a spaced position from said valve seat member for allowing fluid communication between said inlet and said outlet responsive to said fluid pressure within said bore between said seals; conduit means connected into said choke body between said first and said second seals for supplying control fluid pressure to said choke; and spring means on said valve stem for biasing said valve stem and said valve member toward said valve seat member for moving said valve member into engagement with said valve seat member for shutting off fluid communication between said inlet and said outlet when said control fluid pressure decreases below a predetermined value.
 12. A well flow system for a well having a plurality of conduits extending into said well from the surface and in fluid communication with each other in said well, said system including: a fluid flow control manifold for supplying fluid to and receiving fluid from said conduits of said well comprising: an input line connected to a source of fluid pressure; a return line to said source of fluid pressure; a first connecting line from said input line to said return line; a second connecting line from said input line to said return line in parallel flow relationship with said first line; at least two valves at spaced locations in said first connecting line; at least two valves at spaced locations in said second connecting line; a first discharge-return line connected at one end to one of said conduits in said well and at its other end into said first connecting line between said spaced valves in said line; a second discharge-return line connected at one end to another of said conduits in said well and at its other end into said second connecting line between said spaced valves in said line; and choke means in said return line downstream of the connection of said return line into said first and second connecting lines for maintaining a back pressure in said return line upstream thereof.
 13. A well flow system and fluid flow control manifold as defined in claim 12 wherein said return line includes at least two parallel flow portions, automatic choke means in one of said return line parallel portions, fluid pressure communicating means between said automatic choke means and said input and return lines for selectively communicating said automatic choke means with either of said input and return lines, manual choke means in the other of parallel portion of said return line, and valve means in said return line for selectively directing fluid in said return line through either of said parallel portions of said return line through either said automatic choke or said manual choke.
 14. A well flow system and fluid flow control manifold as defined in claim 13 including flowmeter means in said input line, flowmeter means in said return line, fluid pressure measuring means in said input line, and fluid pressure measuring means in said return line.
 15. A well flow system and fluid flow control manifold as defined in claim 13 including portable platform means, bracket means connected between said platform means and a portion of said manifold lines for supporting said manifold in a readily movable status, and coupling means on each of said input, return, and discharge-return lines for releasably connecting said manifold with said conduits providing input and return well flow passages and with said fluid pressure source.
 16. A well flow system and flow conTrol manifold as defined in claim 15, wherein said portions of said connecting lines and said valves connected therein are supported at an upper level above said platform means and said manual and automatic chokes and portions of lines connected therewith are supported therebelow at a lower level whereby the length and width of said manifold and said platform means are minimized.
 17. A well flow system for a well having a pair of flow conductors extending from the surface into said well and flow connected near their lower ends, including: a fluid flow control manifold for supplying fluid to and receiving fluid from said flow conductors comprising: an input line connected to a source of fluid pressure; a first discharge-return line connected to one of said flow conductors; a conduit line connected at one end of said input line and at the other line to the other end of said first discharge-return line; a valve in said conduit line; a first connector line connected at a first end into said conduit line between said valve therein and said first discharge-return line; a valve in said first connector line; a second connector line connected at a first end into said conduit line between said valve therein and said input line; a valve in said second connector line; a third connector line connected at one end to a second end of said first connector line and connected at the other end to a second end of said second connector line; a valve in said third connector line; a second discharge-return line connected at one end to the other of said flow conductors and at its other end connected into said second and third connector lines between said valves therein; a return-line connected into said first and third connector lines between said valves therein; said return line including first and second parallel branch line portions, each of said branch line portions having a valve connected therein for controlling flow therethrough; a manual fluid flow choke in said first return branch line portion downstream of said valve therein; an automatic fluid flow choke connected in said second return branch line portion downstream of said valve therein; and fluid pressure communication means connected between said automatic choke and said return line for controlling said automatic choke responsive to fluid pressure in said return line.
 18. A fluid flow control manifold as defined in claim 17 including fluid pressure communication means connected between said automatic choke and said input line, said automatic choke being selectively operable responsive to fluid pressure in either said input line or said return line.
 19. A well fluid flow control system for supplying fluid to and receiving fluid from a pair of flow conductors extending from the surface into said well and flow connected at their lower ends comprising: an input line connected to a source of fluid pressure; a return line; a first connecting line from said input line to said return line; a second connecting line from said input line to said return line in parallel flow relationship with said first line; valve means associated with said connecting lines for selectively directing fluid from said input line through either one of said connecting lines and for selectively directing fluid from the other one of said connecting lines into said return line; a first discharge-return line connected at one end to one of said well flow conductors at the surface and at its other end into said first connecting line for conducting fluid between said manifold and said well flow conductors; a second discharge-return line connected at one end to the other of said well flow conductors at the surface and at its other end into said second connecting line for conducting fluid between said manifold and said well flow conductors; and choke means in said return line for imposing a predetermined back pressure on fluids flowing in said flow conductors and said manifold upstream of said choke means.
 20. A well fluid flow control system for supplying fLuid and receiving fluid from a pair of flow conductors extending from the surface into said well and flow connected at their lower ends comprising: an input line connected to a source of fluid pressure; a return line; a first connecting line from said input line to said return line; a second connecting line from said input line to said return line in parallel flow relationship with said first line; first valve means at the juncture of said input line with said first and second connecting lines for selectively communicating said input line with either of said first connecting line and said second connecting line; second valve means at the juncture of said return line with said first and second connecting lines for selectively communicating said return line with either of said first connecting line and said second connecting line; a first discharge-return line connected at one end into said first connecting line and connected at its other end to a lubricator connected to one of said well flow conductors; a second discharge-return line connected at one end into said second connecting line and connected at its other end to a lubricator connected to the other of said well flow conductors; and choke means in said return line downstream of the connection of said return line with said first and second connecting lines maintaining a back pressure in said return line upstream of said choke means.
 21. Apparatus for servicing a well having a plurality of well conduits extending into said well which comprises in combination: support means; manifold means comprising a plurality of conduit means arranged on said support means; one end of each of said conduit means extending from said support means and adapted to be connected to said well conduits extending into said well; each said conduit means being connected with lubricator means for inserting a well tool into one of said well conduits; a radius bend in at least one of each of said well conduits and conduit means; first and second connecting conduit means connected to said conduit means; and valve means in each of said connecting conduit means for opening and closing said connecting conduit means; one of said conduit means being adapted to be connected to pump means and the other being adapted to be connected to tank means connected to said pump means; whereby a tool inserted into said lubricator means is pumpable through said conduit means and said conduits extending into said well.
 22. Apparatus in accordance with claim 21 in which the support means is portable.
 23. Well apparatus which comprises: a plurality of well conduits extending into a well; portable support means; manifold means comprising a plurality of conduit means arranged on said support means; one end of each of said conduit means extending from said support means and releasably connected to one of said conduits extending into said well; each of said conduit means being connected with openable and closable lubricator means for inserting a well tool into at least one of said well conduits; a radius bend in at least one of each of said well conduits and conduit means; at least first and second connecting conduit means connecting said conduit means; pump means; tank means; one of said conduit means being releasably connected to said pump means and the other of said conduit means being releasably connected to said tank means; and means connecting said pump and tank means; whereby said support means, said conduit means, and said connecting conduit means may be disconnected from said well conduits extending into said well and from said pump and tank means and connected to similar means on another well.
 24. Apparatus for servicing a well having a plurality of well conduits extending into said well which comprises in combination: support means; a plurality of conduit means arranged on said support means; one end of each of said conduit means extending from said support means and adapted to be connected to said well conduits extending into said well; the other end of each said conduit means being provided with openable closure means for inserting a well tool into said conduit means; a radius bend in at least one of each of said well conduits and conduit means; first and second branched conduit means having branches connected to said conduit means and said branched conduit means having a free end; and valve means in each of said branches for opening and closing the branches of said branched conduit means; the free end of said branched conduit means being adapted to be connected to pump means and being adapted to be connected to tank means connected to said pump means; whereby a tool inserted into said conduit means is pumpable through said conduit means and said conduits extending into said well.
 25. Apparatus in accordance with claim 24 in which a radius bend is provided in each of said conduit means.
 26. Apparatus in accordance with claim 24 in which a radius bend is provided in each of said well conduits.
 27. Apparatus in accordance with claim 24 in which at least one of said branched conduit means is provided with a valve means adjacent the free end and past the branches thereof.
 28. A system for use with a completion system in which there are two strings of tubing suspended in the well bore with means in said well fluidly connecting said strings for use with pump down tool equipment: pump means for supplying hydraulic fluid under pressure; a first conduit means connected to one of said tubing strings; second conduit means connected to the other of said tubing strings; means to selectively connect the outlet of said pump means to either of said first and second conduit means; a connecting conduit between said first conduit means and said second conduit means with two valves therein; a production conduit means connected to said connecting conduit between said valves, said production conduit means comprising a first conduit having a valve therein and a production flow choke downstream of such valve, and a second conduit in parallel with said first conduit and having a valve therein and means downstream of said valve to hold a selected back pressure, regardless of varying flow rate, on the one of said conduit means not connected to said pump means.
 29. In combination with a well system having at least first and second interconnected tubing strings arranged therein to provide a circulation path of fluid down one tubing string and up the other tubing string, apparatus which comprises: a back pressure manifold connected to said two tubing strings and to fluid pumping and storage means; said back pressure manifold comprising a first conduit having means for connecting it to said pumping and storage means and to the first tubing string; a first flowmeter and pressure measuring means in said first conduit; a second conduit connected to said second tubing string and connected to said first conduit between said first flowmeter and pressure measuring means and the first tubing string; a third conduit having means for selectively connecting it in flow communication either to the first conduit intermediate the connection between the first and second conduits and the first tubing string or in separate flow communication to the second conduit; second flowmeter and pressure measuring means in said third conduit downstream from the means for selectively connecting it to said first conduit on the said second conduit; variable choke means in said third conduit downstream from said second flowmeter and pressure measuring means for holding pressure on one of said tubing strings to provide a desired rate of flow through said interconnected tubing strings; said third conduit having means for connecting it to said fluid pumping and storage means; and valve means in said first, second and third conduits between the points of connection of said conduits with each other for directing flow in either direction in said first and second tubing strings; said flowmeter and pressure-measuring means comPrising means for determining the fluid flow rates and pressures of fluids flowing through said conduits for varying said choke means for controlling flow through said interconnected tubing strings.
 30. Apparatus in accordance with claim 29 in which bypass means is provided in said third conduit for bypassing said choke means.
 31. Apparatus in accordance with claim 29 in which the choke means is automatic.
 32. Apparatus in accordance with claim 29 in which the choke means is manual.
 33. The combination of claim 29 wherein said flowmeter and pressure-measuring means comprises recording means providing a written record of the fluid flow rates and pressures of the fluids flowing through the manifold conduits for use in varying the setting of the variable choke means for controlling flow through the interconnected tubing strings.
 34. A well flow system comprising: means extending into a well from the surface providing first and second flow passages therein; means within said well providing fluid communication between said first and said second flow passages permitting fluid circulation through said well from the surface end thereof; and mainfold means communicating with said surface ends of said flow passages of said well, said manifold means including an input flow passage portion connected to a source of fluid pressure and a return flow passage portion having fluid choke means for imposing a predetermined back pressure on fluid in said return flow passage portion comprising an automatic choke selectively operable responsive to either the pressure at which fluid is supplied to said manifold means or the pressure of fluid flowing in said return flow passage portion, a manual choke disposed in parallel fluid flow relationship with said automatic choke, and valve means for selectively directing fluid flow through either of said chokes, fluid pressure and flow rate monitoring means for determining input and return fluid flow rates and pressures in said system for controlling flow through said system by means of said choke means, and means for selectively communicating either one of said flow passages of said well with one of said input and return passage portions and the other of said flow passages with the other of said input and return passage portions.
 35. A well flow system of the character set forth in claim 34 wherein said automatic choke comprises: a body having a bore and an inlet to said bore and an outlet from said bore with an annular valve seat member supported in said bore of said body between said inlet and said outlet; a tubular valve stem slidably supported within said bore of said body for longitudinal movement therein; an annular valve member supported on said valve stem and movable therewith between engagement with said valve seat member for closing off flow through said choke body between said inlet and said outlet and spaced from said valve seat member for permitting fluid communication between said inlet and said outlet; and means providing a first seal within said choke body around said valve stem; means providing a second seal within said choke body around said valve stem spaced along said valve stem from said first seal; the line of sealing engagement of said first seal with said valve stem being less than the line of sealing engagement of said second seal with said valve stem whereby fluid pressure applied to said valve stem between said first and second seals within said choke body biases said valve stem away from said seat member for moving said valve member to a spaced position from said valve seat member for allowing fluid communication between said inlet and said outlet responsive to said fluid pressure within said bore between said seals; conduit means connected into said choke body between said first and said second seals for supplying control fluid pressure to said choke; and spring means disposed between said valve stem and said choke body for biasing said valve stem and said valve member toward said vAlve seat member for moving said valve member into engagement with said valve seat member for shutting off fluid communication between said inlet and said outlet when said control fluid pressure decreases below a predetermined value.
 36. A well flow system of the character set forth in claim 34 wherein said fluid pressure and flow rate monitoring means comprises: recording means providing a written record of such fluid pressure and flow rates of the fluids flowing in the system for use in varying the setting of said fluid choke means for controlling flow through the well flow passages.
 37. A well flow system comprising: means extending into a well from the surface providing first and second flow passages therein: means within said well providing fluid communication between said first and second flow passages permitting fluid circulation through said flow passages in said well from the surface end thereof; manifold means communicating with such surface ends of said flow passages of said well and including: an input line connected to a source of fluid pressure; a return line; a first connecting line from said input line to said return line; a second connecting line from said input line to said return line in parallel flow relationship with said first line; at least two spaced valves in said first connecting line; at least two spaced valves in said second connecting line; a first discharge-return line connected at one end into said said second connecting line between said spaced valves in said line and at the other end to one of said well flow passages; a second discharge-return line connected at one end into said second connecting line between said spaced valves in said line and at the other end to said other well flow passage; variable choke means connected in said return line downstream of the connection of said return line into said first and second connecting lines and including: an automatic choke having a control fluid chamber selectively communicatable with said input line and said return line for selectively operating said choke responsive to fluid pressure in either said input line or said return line for imposing a controlled back pressure on said well flow passages through said manifold means; a manual choke connected in parallel flow relationship with said automatic choke in said return line; flowmeter means in said input line; flowmeter means in said return line; fluid pressure measuring means in said input line; and fluid pressure measuring means in said return line; said flowmeter means and said fluid pressure measuring means comprising means for determining input and return fluid flow rates and pressures in said system for controlling flow through said flow passages of said well passages by means of said choke means.
 38. A well flow system of the character set forth in claim 37 wherein said flowmeter means and said fluid pressure measuring means comprise recording means providing a written record of the fluid pressures and flow rates of the fluids flowing through the input line and return line for use in setting said variable choke means for controlling flow through the flow passages in the well.
 39. A well flow system for a well having a plurality of a extending into said well from the surface and including: a fluid flow control manifold for supplying fluid to and receiving fluid from said conduits of said well and comprising an input line connected to a source of fluid pressure; a return line to said source of fluid pressure; a first connecting line from said input line to said return line; a second connecting line from said input line to said return line in parallel flow relationship with said first line; at least two valves at spaced locations in said first connecting line; at least two valves at spaced locations in said second connecting line; a first discharge-return line connected at one end to one of said conduits in said well and at its other end into said first connecting line between spaced said valves in said line; a second discharge-return line connected at one end to another of said conduits in said well and at its other end into said second connecting line between said spaced valves in said line; choke means in said return line downstream of the connection of said return line into said first and second connecting lines for maintaining a back pressure in said return line upstream thereof and comprising at least two parallel flow conduit sections; automatic choke means in one of said parallel flow conduit sections of said return line; fluid pressure communicating means between said automatic choke means and said input and return lines for selectively communicating said automatic choke means with either of said input line and said return line; manual choke means in another of said parallel flow conduit sections of said return line; and valve means in said return line for selectively directing fluid in said return line through either of said parallel flow conduit sections of said return line through either of said automatic choke or said manual choke; flowmeter means in said input line; flowmeter means in said return line upstream of said choke means; fluid pressure measuring means in said input line; and fluid pressure measuring means in said return line between said flowmeter means in said line and said choke means; said flowmeter means and fluid pressure measuring means comprising means for determining the fluid flow rates and pressures of fluids flowing through said conduits for controlling flow through the flow passages in the well by means of said choke means.
 40. A well flow system of the character set forth in claim 39 wherein said flowmeter means and said fluid pressure measuring means comprise recording means providing a written record of the fluid pressures and flow rates of the fluids flowing through said connecting lines of the manifold means for use in varying the setting of said manual choke or said automatic choke for controlling flow through the conduits in the well. 